Objective: UPlanSApo 100x oil/1.40	Exposure: 100 ms
Microscope: Olympus DSU/IX81	Gain: 3
Camera: Hamamatsu ImagEM	Interval: 7 min

Mammalian cells in culture are a very popular and useful system for detailed studies of mitosis using optical microscopy. Perhaps the most recognizable and most familiar phase of mitosis is termed metaphase, a stage where the chromosomes, attached to the kinetochore microtubules, begin to align in a single plane (known as the metaphase plate) midway between the spindle poles. The kinetochore microtubules exert tension on the chromosomes, which move in erratic back-and-forth motion. At this point the entire spindle-chromosome complex is now ready for the next event, separation of the daughter chromatids. Metaphase, one of the most critical stages in mitosis, occupies a substantial portion of the division cycle. The primary reason for this extended interval is that dividing cells pause until all of their chromosomes are completely aligned at the metaphase plate. This sets the stage for chromosome separation in the next stage of mitosis, termed anaphase. In the digital video presented in this section, pig kidney epithelial cells (LLC-PK1 line) are expressing mCherry fluorescent protein fused to human histone H2B (red fluorescence) and mEGFP fused to the microtubule end-binding protein, EB3 (green fluorescence).